What Problem May Occur If an Economy Has Too Few

What problem may occur if an economy has too few banks or none at all?

A) The economy will support nearly the same standard of living as banks.
B) The economy will be subject to periods of high unemployment alternating with periods of high employment but very high inflation.
C) The economy will be underdeveloped, with a possible increase in unemployment and business failures.
D) The economy may "overheat" and inflation may become a problem.